Granulomatous diseases are highly destructive tissue reactions which often involve the lung. Clinically, pulmonary granulomatous inflammation is difficult to manage, requiring potent anti-inflammatory drugs that can compromise the patient's metabolic and immunologic integrity. Clearly, understanding the basic immunoregulatory mechanisms operative in the initiation, maintenance and resolution of these inflammatory processes may afford better approaches for treatment of these diseases. While most studies have examined the function of granuloma macrophages, few studies have investigated the role of lymphocytes, particularly natural killer (NK) lymphocytes, in the initiation, maintenance and resolution of granulomatous inflamation. This proposal will focus on the immunoregulatory effects that subsets of NK lynphocytes have on the various stages of granuloma development. This study will specifically focus on: 1) The isolation and characterization of lymphocyte subsets (particularly natural killer cells) obtained from hypersensitivity lung granulomas induced by embolization of Schistosome mansoni eggs. This study will involve extensive flow cytometric surface marker analysis and functional NK assays; 2) An examination of the immunoregulatory effects of NK cells on the development of S. mansoni egg induced lung granulomas. This will involve a) in vivo depletion of NK cells by administration of cytotoxic antibodies reactive with NK specific surface markers; b) Adoptive transfer of cells selectively enriched for or depleted of NK cells; c) Adoptive transfer of NK cells positively selected by fluorescent activated cell sorting; and d) Adoptive transfer of cells from mice genetically NK deficient (beige) or mature T cell deficient (nude). Assessment of the effects of these treatments will be determined by morphometric analysis of lung granulomas 4, 8, 16 and 32 days after embolization of S. mansoni eggs and complete surface marker analysis and NK function of lymphocyte subpopulation within the spleens and lungs of responding animals. The effects of NK cells on soluble schistosome egg antigen (SEA) induced B cell immunoglobulin production or lymphokine production (migration inhibitory factor (MIF) and interleukin-2 (IL-2) will be determined using in vitro systems. Finally, we will analyze the dynamic interplay between NK cells and granuloma derived macrophages (taken at various stages of granuloma development) by determining how macrophage derived cytokines (IL-1) and arachidonic acid metabolites effect NK function.